[media] media: rc: nuvoton-cir: improve nvt_hw_detect

Check for the case that no Nuvoton chip is found on either EFM port.
Also move the position of nvt_efm_disable to reduce the time the
EFM ports are locked.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>